Wirebonding fixture and casting mold
The present disclosure involves a method and apparatus for attaching two electrical dies by wire bonding and then encasing the assembly in a protective casting that works by arranging two dies into a fixture conducive to wire bonding. Doped epoxy may be immediately dispensed over the assembly to form a near-net-shape protective cover, or Drive Can.
1. An apparatus for fabricating an ultrasound transducer assembly, comprising:
a bottom plate that includes a first cavity, wherein the first cavity includes a first pocket configured to accommodate an ultrasound transducer die and a second pocket configured to accommodate an Application Specific Integrated Circuit (ASIC) die;
a bonding plate configured to be selectively positioned over and against the bottom plate, the bonding plate including a recess, wherein when the bonding plate is positioned against the bottom plate:
the ultrasound transducer die and the ASIC die would be trapped in a fixed position, and
the recess exposes a portion of the first pocket and a portion of the second pocket:
a molding plate configured to be selectively positioned over and against the bottom plate after the bonding plate has been removed, wherein the molding plate includes:
a second cavity that is aligned with the first cavity when the molding plate is positioned against the bottom plate, such that the first and second cavities collectively define a shape of a transducer assembly,
a first opening that is coupled to the second cavity, wherein the first opening exposes a portion of the first pocket when the molding plate is positioned against the bottom plate,
a second opening that is coupled to the second cavity, wherein the second opening exposes a portion of the second pocket when the molding plate is positioned against the bottom plate, and
a third opening that is in fluid communication with the first and second cavities such that a fluid can flow into the first and second cavities through the third opening; and
a first shut-off pin configured to be positioned inside the first opening of the molding plate such that, when the molding plate is positioned against the bottom plate, the first shut-off pin makes physical contact with an upper surface of the ultrasound transducer die, wherein the first shut-off pin extends beyond the second cavity.
2. The apparatus of claim 1 , further comprising a second shut-off pin configured to be positioned inside the second opening of the molding plate such that, when the molding plate is positioned against the bottom plate, the second shut-off pin makes physical contact with an upper surface of the ASIC die.
3. The apparatus of claim 2 , wherein the second shut-off pin extends beyond the second cavity.
4. The apparatus of claim 1 , wherein the molding plate further includes a vent gap that is in fluid communication with the second cavity.
5. The apparatus of claim 1 , wherein the molding plate is a first molding plate, and further comprising a second molding plate that is configured to be positioned over and against the first molding plate, wherein the second molding plate includes a fourth opening that is in fluid communication with the third opening.
6. The apparatus of claim 1 , wherein the transducer assembly has a curved tip.
7. The apparatus of claim 6 , wherein the curved tip is located proximate to the ultrasound transducer die and has a spherical shape.
8. The apparatus of claim 1 , wherein the recess of the bonding plate is configured to allow for an electrical connection between the ultrasound transducer die and the ASIC die.
9. The apparatus of claim 8 , wherein the electrical connection comprises a bond wire.
10. The apparatus of claim 1 , further comprising a second ejector pin in contact with a back surface of the ASIC die.
11. The apparatus of claim 1 , wherein the ultrasound transducer die comprises a Piezoelectric Micromachined Ultrasound Transducer (PMUT) die.
12. The apparatus of claim 1 , wherein the ultrasound transducer die comprises a Capacitive Micromachined Ultrasound Transducer (CMUT) die.
13. The apparatus of claim 1 , further comprising a first ejector pin in contact with a back surface of the ultrasound transducer die.
14. An apparatus for fabricating an ultrasound transducer assembly, comprising:
a bottom plate that includes a first cavity, wherein the first cavity includes a first pocket configured to accommodate an ultrasound transducer die and a second pocket configured to accommodate an Application Specific Integrated Circuit (ASIC) die;
a bonding plate configured to be selectively positioned over and against the bottom plate, the bonding plate including a recess, wherein when the bonding plate is positioned against the bottom plate:
the ultrasound transducer die and the ASIC die would be trapped in a fixed position, and
the recess exposes a portion of the first pocket and a portion of the second pocket;
a molding plate configured to be selectively positioned over and against the bottom plate after the bonding plate has been removed, wherein the molding plate includes:
a second cavity that is aligned with the first cavity when the molding plate is positioned against the bottom plate, such that the first and second cavities collectively define a shape of a transducer assembly,
a first opening that is coupled to the second cavity, wherein the first opening exposes a portion of the first pocket when the molding plate is positioned against the bottom plate,
a second opening that is coupled to the second cavity, wherein the second opening exposes a portion of the second pocket when the molding plate is positioned against the bottom plate, and
a third opening that is in fluid communication with the first and second cavities such that a fluid can flow into the first and second cavities through the third opening; and
a first ejector pin in contact with a back surface of the ultrasound transducer die.
15. The apparatus of claim 14 , further comprising a first shut-off pin configured to be positioned inside the first opening of the molding plate such that, when the molding plate is positioned against the bottom plate, the first shut-off pin makes physical contact with an upper surface of the ultrasound transducer die.
16. The apparatus of claim 15 wherein the first shut-off pin extends beyond the second cavity.
17. The apparatus of claim 14 , further comprising a second ejector pin in contact with a back surface of the ASIC die.
18. The apparatus of claim 14 , further comprising a second shut-off pin configured to be positioned inside the second opening of the molding plate such that, when the molding plate is positioned against the bottom plate, the second shut-off pin makes physical contact with an upper surface of the ASIC die.
19. The apparatus of claim 18 , wherein the second shut-off pin extends beyond the second cavity.
20. The apparatus of claim 14 , wherein the molding plate further includes a vent gap that is in fluid communication with the second cavity.
21. The apparatus of claim 14 , wherein the molding plate is a first molding plate, and further comprising a second molding plate that is configured to be positioned over and against the first molding plate, wherein the second molding plate includes a fourth opening that is in fluid communication with the third opening.
22. The apparatus of claim 14 , wherein the recess of the bonding plate is configured to allow for an electrical connection between the ultrasound transducer die and the ASIC die.
23. The apparatus of claim 22 , wherein the electrical connection comprises a bond wire.
24. The apparatus of claim 14 , wherein the transducer assembly has a curved tip.
25. The apparatus of claim 24 , wherein the curved tip is located proximate to the ultrasound transducer die and has a spherical shape.
26. The apparatus of claim 14 , wherein the ultrasound transducer die comprises a Piezoelectric Micromachined Ultrasound Transducer (PMUT) die.
27. The apparatus of claim 14 , wherein the ultrasound transducer die comprises a Capacitive Micromachined Ultrasound Transducer (CMUT) die.